Mom, I feel like pulling a Cher from "Moonstruck" -- Snap out of it!
In 15 cruises, I've been on Carnival 6 times, and I can say have never had any problems.
You will love the balcony -- we always book one on longer trips. It's so nice to have that private space outside. The balcony does not take away from the size of the cabin. I smoke, and I can tell you I have never had anyone else's smoke come over. Worst case with a balcony is sometimes you can hear the people next door talking, but this is usually during sailaway. It's rare that you will be out there exactlly every time when your neighbor will be.
I've always had great luck with the food on Carnival (except for the turkey dinner). Read Anne Campbell's newest reviews for Carnival, she notes how the food has improved *a lot*, and Anne knows her stuff.
Yep, those reviewers gotta a rude waiter. In 16 cruises, I have had one -- and he was more mediocre more than anything else.
The deli is my favorite place on board. One time, I saw that they ran out of a certain type of sandwich, but never any horrendous waits or anything.
Same goes with the pool-side grill. Yea, there are going to be longer lines at certain times, but you can just come back when there are less. I ran into a line one time in 6 cruises with Carnival.
I think you need to stop worrying, because you're gonna ruin the trip before you even leave. Expect to have a good time, and you will. Don't get hung up on this or that which is not perfect. Just roll with it.
More than anything, just relax.